Eagle Population Research Articles

Steppe Eagle breeding population surveys in Turkey between 2015 and 2022

The status of the Steppe Eagle (Aquila nipalensis) was unclear in Turkey, which forms the south-western border of the species’ breeding distribution. The status of the species in Turkey has never been clear, as historically only two breeding territories were found and documented in the wider area of Tuz Gölü, which were proved to be active only in some years between 1969 and 1980. One nest in Tuz Gölü was found in some years between 1969 and 1975, while another nest was found in Bolluk Gölü in 1975, and was active also in 1980. There were no published breeding records since 1980 until 2003, when a Steppe Eagle brood was found accidentally in central Anatolia by Hungarian birdwatchers. There were no other published breeding records of Steppe Eagles in Turkey in the twentieth century, although adult birds have been observed in a few occasions in Central and Eastern Anatolia during the breeding season between 1998 and 2015. A short species-specific survey was undertaken by Hungarian and Russian researchers in 2015, which revealed eight potential breeding territories in Kırşehir and Konya provinces, three of them with incubating birds, one with a pair and an active nest, and four further potential territories where mature individuals were observed. Based on these results further surveys have been organized in cooperation of Hungarian and Turkish researchers between 2017 and 2022. Alltogether 38 nests were found of which active breeding attempts were proved in 23 cases. During the surveys 23 potential territories have been identified: 10 territories with detected breeding attempts (incubation or nestling rearing), 5 territories with detected occupancy (territorial pairs or active nests), 6 potential territories (single adult birdsobserved in suitable habitats), and 2 abandoned territories (no activity was observed). The controlled clutches contained 2.00 eggs (n=6), 1.65 nestlings (n=18), and 1.37 fledglings (n=16) on average. Hybridization of Steppe Eagles with Eastern Imperial Eagles (Aquila heliaca) was proved genetically in one case, where a hybrid male bird paired with an imperial eagle female and successfully raised hybrid nestlings in several years. The dispersal and migration of six young steppe eagles and two hybrid juveniles have been tracked with the help of GPS transmitters. The tracked steppe and hybrid eagles moved to the Sahel region for wintering. The surveys also revealed significant potential threats to eagle populations within Turkey, including electrocution, shooting, massive habitat alteration, and infrastructural developments. Therefore, intensive further studies, including active species and habitat conservation measures, are inevitable for the maintenance of the Anatolian Steppe Eagle population, which is most probably in critically endangered status.

Популяционно-генетическая структура степного орла: есть ли надежда на сохранение вида?

For centuries, Steppe Eagle (Aquila nipalensis) had been the most numerous Palearctic Aquila species, but nowadays it has been decreasing in numbers progressively, so in 2015 the IUCN changed the species status to “endangered”. The decrease is evidently related to Steppe Eagles’ electrocution at nesting areas and during migration, poisoning by veterinarian drugs when feeding on agricultural animal carcasses at wintering grounds, steppe fires and total habitat loss combined with loss of prey like susliks. To the contrary, the sister Aquila species, the Imperial Eagle (Aquila heliaca), which exhibits similar biological traits and lives simpatrically to the Steppe Eagle at some parts of areas, shows local increase in numbers and even substitutes the decreasing Steppe Eagle in steppe biomes. In the 1960s, many Palearctic birds of prey came through population decline due to so-called “DDT crisis” – massive pesticide poisoning. To restore the species numbers, specific conservation actions were initiated in Europe to support population numbers and genetic diversity of raptors. Regarding the Steppe Eagle with its nesting area located mostly at Kazakhstan, Russian, Mongolian and Chinese territories, the implications of DDT and electrocution impacts on the population numbers stayed poorly investigated. Meanwhile, loss of genetic stability can be a reason for lasting population decline. Genetic threats like population fragmentation, genetic erosion, and inbreeding depression are believed more prolonged in comparison to anthropogenic impacts and more rarely come under increasing scrutiny of conservation practitioners. However, if exist, they can lead to species extinction regardless of removal of all other threats. The Steppe Eagle population structure stays poorly investigated. In 2018, during the 1st Steppe Eagle conservation international workshop, this problem was highlighted with recommendations for filling this gap. Our presented study was conducted following this recommendation and focused on genetic structure, fragmentation, and effective number comparison of the Steppe Eagle population at the individual samples) and sympatric populations of the Imperial Eagle (over 100 samples). For conservation criteria estimation, we used widespread genetic markers like nuclear microsatellites (9 loci) and mitochondrial control region (D-loop). Also we performed molecular individual tagging and parentage analysis to study the population structure using samples from the numerous Western Kazakhstan population. We also used GIS methods to study geographic fragmentation of populations. The genetic analysis showed that the Steppe Eagle population structure is highly similar to that of the Imperial Eagle but with less genetic diversity and has traces of repeated survival of “population bottlenecks” with huge decline in the number and genetic diversity. Fragmentation analysis showed no genetic isolation of geographically fragmented nesting groups despite the presumed natal phylopatry in accordance with our Steppe Eagle parentage data. Preliminary estimation of the Steppe Eagle population effective numbers by linkage disequilibrium method showed rather high values inspite of the lasting population decline. The molecular coancestry estimation showed more serious decline during the latest bottleneck which was also far below the ancestral Imperial Eagle population at the studied areas. The inbreeding rate for the Steppe Eagle population at the most part of the species areas turned out to outnumber one for the local population of the Imperial Eagle. Our data showed no immediate genetic threats for the Steppe Eagle population restoration and also demonstrated traces of multiple bottlenecks in the species evolution. Still the genetic structure of the species population keeps some traits of modern decline and should be monitored permanently according to the species numbers. Unique population structure patterns of the Steppe Eagle between other Aquilinae species and their conservation aspects are directions for future Aquila nipalensis genetic research.

Movement patterns of juvenile and immature eastern imperial eagles from Bulgaria

Eastern Imperial Eagle (Aquila heliaca) populations in Central Europe and Balkans are non-migratory while most of those in the eastern part of the range are migratory. However, the juveniles from the non-migratory populations disperse over a large area. We studied the movement pattern of juvenile and immature Eastern Imperial Eagle from Southeast of Bulgaria using satellite telemetry. In total, 23 juvenile Eastern Imperial Eagles have been fitted with Argos/GPS transmitters in their nests in Bulgaria in 2008–2013 and seven eagles were tagged with GPS/GSM transmitters in 2021–2022. Dispersal distance varies significantly as some birds reached Israel, Syria, Saudi Arabia, and Africa while others wintered on the Balkan Peninsula and in Turkey. Majority of the birds spent their first winter outside Europe in Anatolia, Middle East, and Africa while three birds wintered in the Southeastern Balkans and one in the island of Crete. In the spring all eagles moved from the wintering areas to Bulgaria, close to their natal areas. Long distance nomadic movements northward during the spring and summer to Central Europe, Ukraine, Belarus and northernmost to Latvia and Russia have been recorded as well. The results indicate that international collaboration should be part of the conservation strategies for the Bulgarian Eastern Imperial Eagle population with Turkey as a key country for conservation interventions.

Орёл-могильник на юго-востоке Казахстана в 2022–2023 годах: распространение, численность, угрозы

Орёл-могильник на юго-востоке Казахстана в 2022–2023 годах: распространение, численность, угрозы

Опыт использования гнездовых платформ для степного орла на юге Костанайской области, Казахстан

Steppe Eagle (Aquila nipalensis) population currently continues to decline in Kazakhstan, the south of the Kostanay region is no exception. The reasons for the decline are of different nature, both abiotic and biotic, and include the following: destruction of nests by land predators (most often Steppe Eagle nests are located on the ground); steppe fires are of great threat, and the fact that some nests are located on trees and bushes does not help, but rather aggravates the situation; destruction of nests by livestock; developing new areas for farms, etc., as a result, Steppe Eagles are forced to leave favorable nesting territories; electrocution on power poles as Steppe Eagles use traverses to build nests. Artificial structures, such as nesting platforms, are widely used to attract raptors. During the implementation of the project “Steppe Eagle Conservation in Kazakhstan” within the international campaign “Flyway Champions”, 35 platforms were installed in favorable Steppe Eagle nesting biotopes in “Saga” and “Altybay” hunting grounds (managed by ACBK – Association for the Conservation of Biodiversity of Kazakhstan) in the South of the Kostanay region in the summer of 2021. The design is made entirely of metal, consists of a support with a cross section of 100×100 mm and a height of 3 m, where 1 m is buried in the ground, and a “basket” with dimensions of 1×1 m installed at the top. Various shrub and tree branches are placed and attached to the “basket”, designed to imitate an active nest. This design is protected from terrestrial predators, and most importantly, from steppe fires. In the breeding season of 2022, Steppe Eagles occupied three platforms, in 2023 – two. It is noteworthy that a pair of eagles used the same nest in both seasons. As an experiment, in 2021 an old nest of Long-Legged Buzzard (Buteo rufinus) was moved to one of the platforms, and in 2023 it was occupied. In 2022, one of three pairs left the nest for unknown reasons after completing it; in the remaining two, a clutch of two eggs was observed; later we observed down feathers, but only one nestling remained in the nest by the time of the departure. In 2023, clutches on two platforms consisted of two eggs each, but later two and one nestling were observed there, having left the nest in the same number. Nesting platforms also serve as a “perch” for a number of birds, and after the use by Steppe Eagles, Indian Sparrow (Passer indicus) occupies them; the number of such a colony reached 13–16 nests. It is also worth noting that sometimes the distance between occupied nesting platform and occupied natural nest is less than 2 km, which suggests that there is a need for this biotechnical activity.

Does the Release of Bonelli’s Eagles from Captive Breeding Nucleus Contribute to Population Rehabilitation?

During the late 1960s, the Bonelli’s Eagle (Aquila fasciata) population in Israel was brought to the brink of extinction, due to a combination of factors. A rehabilitation program set in 2000 included few measures, among them the release of eaglets from a captive breeding nucleus, producing two to seven eaglets yearly. In recent years there is an apparent increase in the number of Bonelli’s Eagle pairs breeding in the wild, including the reoccupation of territories that were abandoned for many years. Yet, there is only little evidence for the recruitment of captive-born eagles into the wild population, and their contribution to its growth is unclear. These subjects are now being examined by a telemetry study, comparing dispersal patterns and survival rates of captive versus nature hatched eagles. The results from the first five years of study show significant differences between these two groups, with captive hatched eagles dispersing much farther away from their natal site compared to the dispersal of wild eagles. The different dispersal patterns may be the reason for the lower survival rates exhibited by the captive hatched eagles, as many of them wander to neighboring countries where they are subjected to shooting and trapping. Moreover, these birds also have a higher tendency to being electrocuted on power lines. Genetic analysis and alteration of the releasing methods are being used in order to check whether the different movement and behavior attributes of the captive-hatched eagles are linked to genetic properties or behaviorally mechanisms during their growth.

Хищные птицы и ветроэнергетика в Казахстане: какие перспективы для орлов?

Хищные птицы и ветроэнергетика в Казахстане: какие перспективы для орлов?

Современные данные о змееяде в Нижегородской области

The article presents current results of a study of Short-Toed Eagle (Circaetus gallicus) distribution, abundance, and ecology in Nizhny Novgorod region. We designed a network of auto routes to survey the area and subsequently covered it in a four-wheel drive vehicle combined with walking through upland bogs and forest margins by foot. Observations were carried out in 30 districts of the region. Hunting Short-Toed Eagles were observed from natural hills through binoculars. Nests were detected based on adult birds’ observations and analysis of satellite images of the surveyed areas. Photo and video recording of birds and nests was carried out using a SLR camera and a quadcopter. In 2015–2023 observations were carried out on 49 breeding territories. A combination of various swamps, burnt areas, and clearings (n=19; 39%) and typical upland bogs associated with pine forests (n=16; 33%) are optimal biotopes for Short-Toed Eagle. However, Short-Toed Eagle occupies both floodplain meadows (n=7; 14%) and fallow lands (n=5; 10%) in the Nizhny Novgorod region, provided that these biotopes are combined with pine forests. Breading territories are least likely to be located in depleted peat quarries (n=2; 4%). Due to peculiarities of the species ecology (vast breeding territories and nests that are difficult to detect), not a single nest was found in the region until 2016. Currently Short-Toed Eagle breeding has been reliably confirmed on eight breeding territories. We found nine nests located on pines. Variants of nest location architectonics are the following: in the upper whorl of a flattened crown (n=6), on side branches in the central part of the crown (n=2), on the “witch's broom” at the top of the tree (n=1). Reproduction timing is recorded from April 20 (the earliest date of egg laying) to August 10 (nestling remains in the nest). Short-Toed Eagle tends to change nests every season. The repeated reproduction in the same nest was recorded for one pair only, and both attempts were unsuccessful. Only Common European vipers and Grass snakes were reliably identified among the prey brought to the nest (n=24). We repeatedly noted neighbouring pairs interacting at borders of breeding territories, furthermore, we observed Short-Toed Eagles’ conflicts with Common Buzzard (Buteo buteo) (n=6) and Greater Spotted Eagle (Aquila clanga) (n=1) during the breeding period. We were able to draw conclusions based on the results of long-term observations on a typical elliptic shape of a Short-Toed Eagle breeding territory with the nest located in one of its focuses. The main route birds took from the nest to hunting grounds runs along the major axis of the ellipse. Short-Toed Eagles hunt in the immediate vicinity of the nests only in bad weather conditions or in case of unsuccessful breeding, when long flights for prey become rare. The longest recorded distance a hunting bird travelled from its nest was 7.2 km. The shortest distance between two neighboring nests is 3.9 km. The current Short-Toed Eagle abundance in the Nizhny Novgorod region is estimated at 80–90 breeding pairs, which is about five times higher than the estimate of the abundance given in the Red Data Book of the Nizhny Novgorod region in 2014. This increase is affected less by the actual dynamic in the number of species because of changes in habitats (formation of extensive burnt areas and overgrown fallows) and more due to special research efforts. We can assume that estimates of the Short-Toed Eagle population in areas adjacent to the Nizhny Novgorod region were repeatedly undervalued. Given the specifics of ecology (stenophage species, consumer of the 3rd–4th order, low breeding potential, the highest size class), this species continues to require increased attention and preservation of a high conservation status.

Species action plan for conservation of an isolated Steppe Eagle population in Turkey

Steppe Eagle (Aquila nipalensis) is a globally Endangered (EN) species according to IUCN Red List, with a breeding range extending through the arid zones of southern Russia and Kazakhstan, from Kalmykia in the west to Dauria in the east. There is a small, isolated breeding population in Turkey, discovered in 2003, which lost contact with the main breeding range. Although there are studies carried out between 2015 and 2021, the size of the isolated population is not exactly known. To protect this small population on the brink of extinction, the General Directorate of Nature Conservation and National Parks (GDNCNP), which is officially responsible for wildlife conservation, programmed to prepare a species action plan in 2021. As part of the “Preparation, Implementation and Monitoring of Species Action Plans for Endangered Species in Turkey within the Concept of a New Methodology”, shortly “Endangered Species” project, Steppe Eagle was selected, based on a prioritization study, to be one of the pilot species for which species actions to be prepared. Field studies were conducted in the 2022 breeding season to identify threats causing stress to the Steppe Eagle. During the breeding studies in 2022, it was determined that 4 pairs of Steppe Eagles were confirmed to be breeding in Central Anatolia, and 4 pairs attempted to breed. During the field studies, threat factors were listed based on direct observations, indirect observations (nest records, mortality records, etc.), and bilateral discussions with local communities. Using the threat analysis adopted by IUCN and adapted to Turkey within the framework of the same project, a national-level threat analysis was conducted. Direct threat factors causing stress to the species were listed as conversion of grasslands into agricultural areas, excessive use of groundwater and surface water leading to the drying of wetlands, power transmission lines, human activities and grazing pressure on breeding islands in wetlands, illegal hunting, predation, researcher pressure, hybridization with Eastern Imperial Eagles (Aquila heliaca), and artificial materials in nests. Additionally, the use of rodent poisons was also identified as a potential threat. As a result of the threat analysis, the threats with the highest level of impact on the species were identified as the conversion of grasslands into agricultural areas and excessive water usage. These threats result in the transformation of steppe habitat and decrease in the species' food sources. Another high-level threat is illegal hunting. The identified threats were transferred to a problem tree and, following the method generated in the “Endangered Species” project, problem tree was transformed to a result chain. In the result chain, the selected results for eliminating/reducing threats were defined by identifying intervention points and transforming them into objectives. Activities were defined to achieve the identified objectives. Within the scope of the 10-year action plan a total of 34 activities were designed under 9 objectives to be achieved. Eight out of the 9 objectives involve conservation, and one involves research-related activities. The aim of the 10-year plan is to conserve and support the breeding population of the species in Turkey.

Новые данные по гнездовой биологии, экологии и состоянию популяции орлана-белохвоста в Дагестане, Россия

Новые данные по гнездовой биологии, экологии и состоянию популяции орлана-белохвоста в Дагестане, Россия

Мониторинг гнездовой группировки степного орла в Актюбинской области (Казахстан) в 2018–2023 годах

Мониторинг гнездовой группировки степного орла в Актюбинской области (Казахстан) в 2018–2023 годах

Многолетняя динамика численности крупных ищных птиц на ключевой орнитологической территории «Камско-Бакалдинские болота» (Нижегородская область, Россия)

Identification of breeding territories and long-term population monitoring has been carried out in the Important Bird Areas (IBA) with a global importance “Kamsko-Bakaldinskiye marshes” since 1980. Five large bird species were studied here: Osprey (Pandion haliaetus), Short-Toed Eagle (Circaetus gallicus), Greater Spotted Eagle (Aquila [Clanga] clanga), Golden Eagle (Aquila chrysaetos), White-Tailed Eagle (Haliaeetus albicilla). In this report we will summarize the results. IBA covers the northern (Zavolzhsky) part of the Lyskovsky and Vorotynsky districts of the Nizhny Novgorod region, as well as the adjacent areas of Borsky, Semenovsky, and Voskresensky districts. Its total area is 3156.0 km2. The largest massif of upland, transitional, and lowland bogs in the Volga River basin is preserved here in its natural state. A significant part of IBA area (2265 km2) is listed as Ramsar wetland of international importance. Kamsko-Bakaldinskiye marshes has undergone significant transformation over the past 50 years. Until the 1980s, intensive logging was carried out here with an excess areas were organized by 1994, covering 54% of IBA area and leading to a decrease in logging volumes. In the 1980s drainage and peat extraction amounted to 1% of an area. Disastrous fires of 1972 and 2010 spread through about 50% of an area. The number of rare raptor species was positively influenced by the implementation of a unique project to install 62 nesting platforms in 1998–2014. Multidirectional vectors – the destruction of habitats and their conservation, combined with compensatory biotechnical measures, superimposed on the general population trends of large raptors in the center of the European part of Russia. As a result, the population dynamics of different species in Kamsko-Bakaldinskiye marshes differs significantly. The population dynamic for four out of five studied species shows a clear positive trend. Thus, the number of Osprey and White-Tailed Eagle has increased by three and six times, respectively. A project that included nesting platform installation had a significant impact on Osprey population. White-Tailed Eagle depended on it to a lesser extent, however, throughout an entire observation period, there was a general positive trend in the abundance of the species in the European part of Russia. The negative impact of catastrophic fires in 2010 on Osprey and White-Tailed Eagle was insignificant. Abundance of Short-Toed Eagle and Greater Spotted Eagle in 2000–2014 wasseverely underestimated. After 2014, additional data were collected, which allowed us to determine the abundance and distribution of these species in studied area, as well as to identify a positive population trend. In 2000–2014, actual Short-Toed Eagle abundance was twice as high as estimates made in the period. Subsequently, a favorable factor for Short-Toed Eagle was the large burnt area left by fires, which the birds used as new hunting grounds. A twofold increase in Short-Toed Eagle population happened in 2011–2023. The difference in estimates of Greater Spotted Eagle abundance in 2014 and 2018 is mainly due to the results of additional research efforts. Breeding territories have been identified in previously poorly studied floodplain habitats. In addition, the number of Greater Spotted Eagle increased slightly after the fires of 2010 destroyed most of its breeding territories in Kamsko-Bakaldinskiye marshes. The number of Golden Eagle significantly increased in 2000–2010 due to the use of nesting platforms. Then it began to decline due to the long-term depression in Mountain Hare and Grouse populations, as well as catastrophic fires that affected most of breeding territories. Thus, Golden Eagle turned out to be the most vulnerable to pyrogenic changes in their habitat. The number of the species has fallen to the lowest point, almost reaching level of the 1980s. Species’ breeding territories are only preserved in areas unaffected by fires. Golden Eagle’s population decline has had a positive impact on populations of other large raptor species, especially noticeable for Greater Spotted Eagle. The emergence of its breeding territories was noted where Golden Eagle’s breeding territories were lost due to fires. Kamsko-Bakaldinskiye Marshes currently remains the most important refugium for rare large raptor species in Nizhny Novgorod Region, where it is advisable to expand and strengthen protected areas and restore permanent implementation of biotechnical projects.

Electrocution Mortality of Imperial Eagle on Medium Voltage Power Lines in Slovakia

Medium-voltage power lines are one of the most important mortality factors of raptors in Slovakia. Among the frequent victims of electrocution are also rare species, such as the Imperial Eagle (Aquila heliaca). Many of the breeding pairs have gradually relocated from the foothills to nearby agrocenoses, with a higher risk of possible electrocution, as they often use the poles for resting. In Slovakia, the problem of electrocution has been the focus for mitigation measures since 1991. Especially the LIFE Energy project (implemented in 2014–2019) brought new insight into this topic, as systematic monitoring of almost 61,000 medium voltage poles was carried out in 2014–2016. Electrocution was defined as the main mortality factor of cadavers found. Almost 80% (2,992 individuals, 35 species) of all identified carcasses (4,353 individuals, 84 species) died as a result of electrocution. Branch and anchor supports and poles with jumpers above the insulators were the most dangerous configuration, accounting for 34.72% of total recorded electrocution fatalities (0.22 carcasses per pole). Systematic monitoring of the Imperial Eagle population has been carried out since 1977, when the abundance of the breeding population was 2–10 breeding pairs. After 2000, the settlement of the lowlands and the associated gradual increase in the breeding population were recorded, facilitated by targeted conservation measures. In 2022, the population reached 90 breeding pairs with 108 fledged nestlings in Slovakia. For the period 1993–2022, a total of 28 cases of Imperial Eagle mortalities were recorded in Slovakia. More extensive monitoring was carried out within the LIFE Energy project (2014–2019) when 16 victims were found, for the other years these are random cases. Therefore, the presented numbers do not reflect the actual mortality rate of the Imperial Eagle on 22 kV lines in Slovakia. The mortalities of individuals were mainly located below the most frequent types of the support poles with pin-type insulators. A serious problem was often observed especially for juveniles and inexperienced individuals during their first flights, landings and take-offs. Lowest mortality risk was identified for measures that allow birds to perch safely on the crossarm in comparison to antiperching elements. Therefore, the grid operators started to prefer the use of supports with safe crossarm configurations (for newly constructed lines) or insulating materials and elements that reflect these findings. The 22 kV medium voltage lines consist of thousands of supporting poles. It is therefore important to set the priority areas (breeding territories, feeding areas, etc.) where the main efforts should be focused primarily. This approach is fully implemented within the cooperation between Raptor Protection of Slovakia and DSOs in Slovakia, and also under project LIFE Danube Free Sky, under which 800 most dangerous poles will be safe for birds. Project is supported by the European Commission under the LIFE programme and the Ministry of the Environment of the Slovak Republic. Satellite transmitters installed on juveniles also help in the identification of priority poles and also bring new insights into the mortality rate (one from six tagged juveniles in 2022 died as a result of electrocution). Prevention of electrocution is especially important in the case of imperial eagle, as the loss of even one individual can have a negative impact on the viability of the local population. Therefore, many identified risky poles are insulated by DSOs on an ad hoc basis. In Slovakia, the protection of wild bird species in relation to their mortality on power lines is required by the national legislation. Only approved protective elements and crossarm designs that have undergone a risk assessment process can be applied. An important aspect of raptor conservation is the communication, mutual trust, and sharing of up-to-date knowledge between all relevant stakeholders.

Does Temporal and Spatial Diet Alteration Lead to Successful Adaptation of the Eastern Imperial Eagle, a Top Predator?

Predator–prey interactions may be linked to different temporal or spatial patterns, including dynamics in prey populations. Therefore, understanding the adaptive capacity and how top predators respond to shifts in prey abundance and availability is crucial for their conservation. In this study, we investigated the diet pattern of the endangered Eastern Imperial Eagle facing long-term and large-scale changes. We studied the abundance variation of its profitable prey, sousliks, and how it reflected on eagle population trajectories in a regional and temporal context. We found a significant diet alteration expressed in large decrease of brown hare (β2 = −0.83), poultry (β2 = −0.81), gulls (β2 = −0.71), and water birds (β2 = −0.57), and an obvious increase of northern white-breasted hedgehog (β2 = 0.61) and doves (β2 = 0.60). Raptors and owls raised their participation (β2 = 0.44), but white stork and different reptiles supplied more biomass. Abundance of European souslik decreased through the studied periods (adjusted R2 = 0.25, p < 0.001) which accounted for the lower proportion of this prey in the eagle’s diet. Nevertheless, the eagle population successfully adapted and significantly increased (β2 = 0.97) in most of the distribution area. The trophic strategy used by this top predator related to opportunistic foraging represents an ecological advantage that allows the species to adapt to different habitats and guarantees its future. The observed prolonged diet alteration could result in a significant negative attitude among different groups such as hunters, pigeon fanciers, and poultry keepers towards eagles. Therefore, enhanced communication with key stakeholders is needed. Conservation efforts should be focused also on the preservation of the species’ main foraging habitats and the restoration of damaged ones so as to maintain the good conditions of both primary food source and subsequent prey.

The avoidance of living in the vicinity of a top predator: the coexistence of the black stork and the white-tailed eagle in NE Poland

The black stork Ciconia nigra is a rare species of bird that inhabits old forests near wetlands. The early 21st century has brought a regress of its population in north-eastern Poland. We verified the assumption that an important reason for the observed changes was the colonization of the study area by white-tailed eagle Haliaeetus albicilla, because we observed a correlation between decreasing numbers of the black stork and increasing numbers of the eagle. Based on the long-term monitoring, we analyzed changes in the numbers and distribution of the black storks’ nests and compared the colonization of the study area by the white-tailed eagle in the most extensive forest complex in Poland. We found 42 occupied territories of storks and no eagles in 1989 within the study area. In 2019, there were just 23 stork pairs, but the population of eagles increased to 13. We found a correlation between the rate of decline of the black storks population and the increase in the white-tailed eagles. In the first half of study period, storks’ nests have been distributed randomly, after which they became clustered. The pattern of nests distribution was influenced by the increase in the population of the eagle over time, with this ensuring the aggregation of the nests of storks in places more distant from the nests of eagles. Similarly, the nearest neighbor distance of storks’ nests was dependent on distances from the nests of eagles and the shares of territory accounted for by forests. We surmise that changes in the population size of storks were induced mainly by the growth of population of eagles. Storks avoided occupying nests less than 4.6 km from the eagles’ nests. Our study suggests that the determining role can be played by fear of the predator. Overall, it must be concluded that the protection of top predators can affect other co-occurring species in unexpected ways.

The Great spotted eagle <i>Aquila clanga</i> in the Altai Territory and Altai Republic, Russia

Aim. To summarise information provided so as to allow us to compile a modern understanding of the breeding ranges, abundance and breeding biology of the Great Spotted Eagle Aquila clanga, a rare species in the Altai Territory and the Altai Republic.Material and Methods. While studying the distribution, abundance and nesting biology of the Great Spotted Eagle, we used generally accepted methods with certain modifications. The species was observed during foot and car surveys. To get an idea of the distribution of the spotted eagle in the region, an analysis of available sources was carried out, including materials from the Red Data Book of the Altai Territory and other relevant information resources.Results. Nesting groups of a feathered predator are characterised by uneven spatial distribution. This is due to the habit of the spotted eagle to gravitate to wetlands and floodplain lands in high‐trunk mixed forests, alternating with meadow‐pasture and field landscapes. In ribbon and acquisition forests, as well as in wildlife sanctuaries located on their territory, there has been a rapid trend towards a decrease in the population of the species, primarily due to selective felling of vegetation and disturbance of the birds during the nesting period. In this regar, there is a need to expand and deepen ornithological studies aimed at improving environmental measures for the Great Spotted Eagle.Conclusions. Protection of this species should be combined with inevitable criminal or administrative punishment of poachers and illegal forest users, who are involved in destructive environmental activities in the region discussed. Otherwise, the progressive extinction of the Great Spotted Eagle population in Altai will reach a critical point in forthcoming years.

Experimental and natural infections of white-tailed sea eagles (Haliaeetus albicilla) with high pathogenicity avian influenza virus of H5 subtype.

White-tailed sea eagle (Haliaeetus albicilla), a regionally rare species of raptor, is threatened in several countries. To assess the risk of H5 high pathogenicity avian influenza (HPAI) viral infection in rare bird species, we performed experimental infections with a GS/GD96-lineage H5N6 HPAI virus of clade 2.3.4.4e in white-tailed sea eagles. Additionally, during the winter of 2020–2021 in Japan, we accidentally encountered a white-tailed sea eagle that had a fatal outcome due to natural infection with a GS/GD96-lineage H5N8 HPAI virus of clade 2.3.4.4b, allowing us to compare experimental and natural infections in the same rare raptor species. Our experiments demonstrated the susceptibility of white-tailed sea eagles to the GS/GD96-lineage H5 HPAI virus with efficient replication in systemic organs. The potential for the viruses to spread within the white-tailed sea eagle population through indirect transmission was also confirmed. Comprehensive comparisons of both viral distribution and histopathological observations between experimentally and naturally infected white-tailed sea eagles imply that viral replication in the brain is responsible for the disease severity and mortality in this species. These findings provide novel insights into the risk assessment of H5 HPAI viral infection in white-tailed sea eagles, proper diagnostic procedures, potential risks to artificially fed eagle populations and persons handling superficially healthy eagles, potential impact of intragastric infection on eagle outcomes, and possibility of severity of the disease being attributed to viral replication in the brain.

Research on Multi-objective Optimization of Freight Train Operation Process Based on Improved Bald Eagle Search Algorithm

<p>To study the optimization problem of freight train operation process under complex line conditions, this paper adopts the freight train multi-particle model to establish the multi-objective optimization model of the freight train. Aiming at the problem of difficult optimization caused by complex line conditions, a two-step method is used to find the optimal operation strategy of the freight train. Firstly, the greedy algorithm is used to select the optimal working condition sequence. Secondly, the multi-objective optimization algorithm is used to obtain the position of the ideal working condition transition point. By introducing the idea of non-dominated sorting, an improved multi-objective bald eagle search algorithm is proposed to optimize the operation process of freight trains. This algorithm adopts the evolution method of combining bald eagle population renewal with adaptive Gaussian mutation, and introduces preference information to increase the rationality of population evolution. The simulation results show that the optimal operation strategy of freight train selected by two-step method is in line with the actual operation situation, and the proposed multi-objective bald eagle search algorithm considers both convergence and distribution. The results can satisfy the preference of decision-makers, which can provide a reference target speed curve for railway workers.</p> <p> </p>

Policy and the social burden of bald eagle recovery

AbstractOne of the challenges of applying endangered species policy on private property is striking an equitable balance between species protection and civil liberties. The future of many imperiled species depends on a public‐private trust. We estimate the social burden of managing bald eagles on private lands within the lower Chesapeake Bay (1976–2016). We quantify the area of private and government‐owned land deemed critical around nests and estimate the value of private properties as an index of burden. The bald eagle population increased from 30 to 1052 breeding pairs and the land within nest buffers increased from 384 to 10,670 ha with >80% on private lands. Estimated value of private property “under guidelines” increased more than 900 fold. More than 94% of this burden was imposed after eagles reached recovery goals. Restricting activities on private lands to achieve diminishingly small conservation benefits threatens to undermine landowner participation in conservation efforts.

Kleptoparasitic interactions by bald eagles (Haliaeetus leucocephalus) during marine mammal foraging events

Abstract Stealing of food items from another animal, or kleptoparasitism, has been well studied in bird species. Bald eagles are known kleptoparasites of other birds and occasionally other species, however kleptoparasitic interactions with mammals are relatively uncommon. We describe instances of bald eagles taking, or attempting to take, fish and mammal prey from three species of cetaceans (bottlenose dolphins (Tursiops truncatus), harbour porpoises (Phocoena phocoena vomerina) and killer whales (Orcinus orca)) and one species of pinniped (harbour seal (Phoca vitulina richardii)) on the east and west coast of the United States of America. We discuss possible drivers of this emerging behaviour, including bald eagle population increases, reductions in other prey abundance, and changes in prey choice (for harbour porpoises). Further research is needed to determine if this behaviour is opportunistic in nature, or a more common foraging strategy.